Federation and HA are two distinct features that share some commonproperties but nothing more. You can turn on HA for any selectedNamespace but it is not necessarily needed to be that all Namespaceshave HA.

Perhaps an example will clear it up for you.

I have a local instance that is configured to run several namespaces:ns1, ns2, and ns3 (Federated Namespaces).The namespace ns1 hosts my HBase tables and is critical to me, so Ihave also turned on HA for this namespace alone.The other two namespaces ns2 and ns3 are used only for regular queryjobs so its not yet very important for me to have HA on it. So I runthem without HA.

1 Active NameNode + 1 Passive NameNode (it does the work of the oldSecondary NameNode) for NS1 NameSpace (these are 2 diferent machines)1 NameNode for NS21 NameNode for NS3

but what about the Secondary Name Nodes for NS2 and NS3? or I don´t needit? perhaps I´m mixing concepts....

Thanks again,

Greetings,

ESGLinux2012/12/20 Harsh J <[EMAIL PROTECTED]>

> Hi ESGLinux,>> Federation and HA are two distinct features that share some common> properties but nothing more. You can turn on HA for any selected> Namespace but it is not necessarily needed to be that all Namespaces> have HA.>> Perhaps an example will clear it up for you.>> I have a local instance that is configured to run several namespaces:> ns1, ns2, and ns3 (Federated Namespaces).> The namespace ns1 hosts my HBase tables and is critical to me, so I> have also turned on HA for this namespace alone.> The other two namespaces ns2 and ns3 are used only for regular query> jobs so its not yet very important for me to have HA on it. So I run> them without HA.>> Thus I have 4 NameNode processes in my cluster in all, given my design> above: (2 NNs under ns1, in HA mode) + (1 NN of ns2) + (1 NN of ns3).>> On Thu, Dec 20, 2012 at 10:00 PM, ESGLinux <[EMAIL PROTECTED]> wrote:> > Hi All,> >> > I´m going to test a hadoop cluster and I have a doubt about HA and> > Federation.> >> > With federation I Have a NameNode per namespace and with HA I have an> Active> > NameNode and a standby NameNode.> >> > so, as I have sevaral namespaces, do I need an Active NameNode and a> standby> > nameNode per namespace?> >> > I have read this documentation but It´s not clear for me :-(> >> >> https://ccp.cloudera.com/display/CDH4DOC/Introduction+to+Hadoop+High+Availability> >> http://hadoop.apache.org/docs/r0.23.0/hadoop-yarn/hadoop-yarn-site/Federation.html> >> > Thanks in advance> >> > ESGLinux> >>>>> --> Harsh J>

On Thu, Dec 20, 2012 at 11:09 PM, ESGLinux <[EMAIL PROTECTED]> wrote:> Hi Harsh,>> First thank you very much for your answer,>> following your example:>> You have:>> 1 Active NameNode + 1 Passive NameNode (it does the work of the old> Secondary NameNode) for NS1 NameSpace (these are 2 diferent machines)> 1 NameNode for NS2> 1 NameNode for NS3>> but what about the Secondary Name Nodes for NS2 and NS3? or I don´t need it?> perhaps I´m mixing concepts....>> Thanks again,>> Greetings,>> ESGLinux>>>>> 2012/12/20 Harsh J <[EMAIL PROTECTED]>>>>> Hi ESGLinux,>>>> Federation and HA are two distinct features that share some common>> properties but nothing more. You can turn on HA for any selected>> Namespace but it is not necessarily needed to be that all Namespaces>> have HA.>>>> Perhaps an example will clear it up for you.>>>> I have a local instance that is configured to run several namespaces:>> ns1, ns2, and ns3 (Federated Namespaces).>> The namespace ns1 hosts my HBase tables and is critical to me, so I>> have also turned on HA for this namespace alone.>> The other two namespaces ns2 and ns3 are used only for regular query>> jobs so its not yet very important for me to have HA on it. So I run>> them without HA.>>>> Thus I have 4 NameNode processes in my cluster in all, given my design>> above: (2 NNs under ns1, in HA mode) + (1 NN of ns2) + (1 NN of ns3).>>>> On Thu, Dec 20, 2012 at 10:00 PM, ESGLinux <[EMAIL PROTECTED]> wrote:>> > Hi All,>> >>> > I´m going to test a hadoop cluster and I have a doubt about HA and>> > Federation.>> >>> > With federation I Have a NameNode per namespace and with HA I have an>> > Active>> > NameNode and a standby NameNode.>> >>> > so, as I have sevaral namespaces, do I need an Active NameNode and a>> > standby>> > nameNode per namespace?>> >>> > I have read this documentation but It´s not clear for me :-(>> >>> >>> > https://ccp.cloudera.com/display/CDH4DOC/Introduction+to+Hadoop+High+Availability>> >>> > http://hadoop.apache.org/docs/r0.23.0/hadoop-yarn/hadoop-yarn-site/Federation.html>> >>> > Thanks in advance>> >>> > ESGLinux>> >>>>>>>>> -->> Harsh J>>

> Hi,>> To put it simply: If you use a NameNode, you need a SecondaryNameNode.> In HA-mode, a StandbyNameNode acts as a SecondaryNameNode (so you> don't need to run an extra).>> Either way, you definitely need the checkpoint operation happening and> being monitored for.>> On Thu, Dec 20, 2012 at 11:09 PM, ESGLinux <[EMAIL PROTECTED]> wrote:> > Hi Harsh,> >> > First thank you very much for your answer,> >> > following your example:> >> > You have:> >> > 1 Active NameNode + 1 Passive NameNode (it does the work of the old> > Secondary NameNode) for NS1 NameSpace (these are 2 diferent machines)> > 1 NameNode for NS2> > 1 NameNode for NS3> >> > but what about the Secondary Name Nodes for NS2 and NS3? or I don´t need> it?> > perhaps I´m mixing concepts....> >> > Thanks again,> >> > Greetings,> >> > ESGLinux> >> >> >> >> > 2012/12/20 Harsh J <[EMAIL PROTECTED]>> >>> >> Hi ESGLinux,> >>> >> Federation and HA are two distinct features that share some common> >> properties but nothing more. You can turn on HA for any selected> >> Namespace but it is not necessarily needed to be that all Namespaces> >> have HA.> >>> >> Perhaps an example will clear it up for you.> >>> >> I have a local instance that is configured to run several namespaces:> >> ns1, ns2, and ns3 (Federated Namespaces).> >> The namespace ns1 hosts my HBase tables and is critical to me, so I> >> have also turned on HA for this namespace alone.> >> The other two namespaces ns2 and ns3 are used only for regular query> >> jobs so its not yet very important for me to have HA on it. So I run> >> them without HA.> >>> >> Thus I have 4 NameNode processes in my cluster in all, given my design> >> above: (2 NNs under ns1, in HA mode) + (1 NN of ns2) + (1 NN of ns3).> >>> >> On Thu, Dec 20, 2012 at 10:00 PM, ESGLinux <[EMAIL PROTECTED]> wrote:> >> > Hi All,> >> >> >> > I´m going to test a hadoop cluster and I have a doubt about HA and> >> > Federation.> >> >> >> > With federation I Have a NameNode per namespace and with HA I have an> >> > Active> >> > NameNode and a standby NameNode.> >> >> >> > so, as I have sevaral namespaces, do I need an Active NameNode and a> >> > standby> >> > nameNode per namespace?> >> >> >> > I have read this documentation but It´s not clear for me :-(> >> >> >> >> >> >> https://ccp.cloudera.com/display/CDH4DOC/Introduction+to+Hadoop+High+Availability> >> >> >> >> http://hadoop.apache.org/docs/r0.23.0/hadoop-yarn/hadoop-yarn-site/Federation.html> >> >> >> > Thanks in advance> >> >> >> > ESGLinux> >> >> >>> >>> >>> >> --> >> Harsh J> >> >>>>> --> Harsh J>